Personally I've worked with and come through labs that churned out 30, 40, 50 trainees in the career arc of the PI. I know for sure I don't want that - it's unsustainable, not to mention ethically problematic. However, at the other end of the scale, since becoming a PI 13 years ago I've trained 3 PhDs so far and have 2 more graduating in the next year. Should I stop at "replacing myself" those 5 times, and just not take any more students until I retire in 15 years? The question: what IS a good (ethical, sustainable) number of PhD trainees that a bioscience PI can reasonably expect to have in their lab' during a typical career? Is 5 too many? How about 25?

To Ola, I say: I don't have a good answer for you.

It's really a tragedy of the commons problem. You and I can limit who we train, but if the Big Labs keep churning them out, will our trainees get lost in the shuffle? Or can we argue that we are K-strategists (as opposed to r-) and that we give more to fewer trainees? (and if you know r/K theory, and want a good chortle, google it and "evolutionary psychology" and read some... well... bizarro interpretations)

For years, I've only taken clinical/PhD students, MDs/DMDs/PTs for whom there is more employment flexibility. But mostly I take only postdocs, with the idea that I can add some value to those people: not just marking time till the get job, but give them additional skills/background/credentials. But if a really good basic science type came along, interested in what I do? That would be a hard call.

People in the comments have complained that postdocs are too expensive. This is true if grad students are subsidized by your department, as many are. And if you have to pay your postdoc a reasonable wage, it will be more so. If students aren't subsidized or postdocs are subsidized, then it comes out closer to the same, throwing tuition in with salary for students.

It is worth remembering that training grants can support postdocs (I was the co-PI on one for years). Many also support residents to do a year of research or a fellowship in the middle of residency. This may align in clinical departments, and people working at the edge of basic/clinical research. If institutions realize that grad student stipend + tuition is in the same ballpark as a PD, then that might begin to change. This is part of the education of the "carpet-people" that needs to happen.

So the answer in part is: you need to do what that with which you are comfortable. You need to remember that your trainees are people, who require that you provide them with not just scientific training, but the professionalism necessary to succeed. You need to be able to sleep at night, knowing that you did what is right even when those around you have no trouble justifying dreadful behavior. And, you need to survive. Just be careful of justifying behavior on the basis of survival. On that path lies madness.

Why do we always assume that the goal of training graduate students is to "replace you"? I don't want my students to replace me. I want them to move beyond and do other things. This is how economies grow. Yes, some labs make many professors. Other labs make industry moguls. Other labs make science writers. Most labs make a mix of them.

When I was a young pup, there was no internet. (Really, it's not that old!) There are thousands of jobs that never existed then. Some of those jobs require a PhD.

Moreover, why are we so worried about whether a job "requires a PhD"? Getting a PhD is a great ride. It pays you to do something amazing and fun. Many PhDs, particularly in the sciences that we are talking about (*), pay pretty well for the level of experience. Certainly better than many scutwork jobs. Personally, I think the postdoc holding pattern (**) is a much larger crime than making "too many PhDs".

* There is a very big difference between STEM fields that pay graduate students a living wage (some graduate students in our program buy houses) and humanities that charge students to "teach" them.

** The length of the postdoc is related to the number of other jobs available, not to the number of techniques necessary. This can be most clearly seen in computer science where we've had several dot-com booms and busts.

Getting a PhD is a great ride. It pays you to do something amazing and fun.

Agreed. I often say that there are much worse ways to spend early-to-mid 20s than grad school. Grad school can be a great experience for a person who's curious and driven; you work on cutting edge, really challenging stuff and hang out with some of the smartest people in your generation. Most of my former students are in industry and national labs and they seem very happy. Maybe it helps that I tell them from the get-go, "This is not [FancySchmancySchool] and I am not famous. Getting a faculty position with a PhD from here will be hard. If you want a faculty position, you have to publish well while here, then get a good postdoc and publish well there, and it still might not work out. But you will do great science and I will teach you how to think, write, and give talks like a professional scientist. No one who did a PhD in my group took more than 3-4 months to get a good industry job."

Do departments encourage thesis masters? My adviser didn't, but the departments industry advisory group mentioned it. One industry person pointed out how efficient a 5 yr undergrad/master program was. Seems like a great way to get some research experience, publish and present, and learn some new skills while only taking 1-2 years. Also gives the recipient a small leg up when applying for jobs.

Maybe an interesting middle ground to the issue of too many PhDs, too long of times spent in grad school, etc. Granted, the professors don't get the same kudos as for graduating a PhD.

As I understand it, only the number of PhDs graduated are counted as part of the criteria for R1 status. So at my barely R1 university, PhDs are encouraged, while MS degrees are neither encouraged or discouraged.

Many departments treat MS as ok as long as it's "pay to play" (students pay their own way) or as a stepping stone towards a PhD (or, if the PhD doesn't pan out, something the student can show for their time spent).

I will sound harsh and this is discipline-dependent, but, in my experience, MS-only students are not a good use of my time or grant funds. There's a long ramp-up time in my field, so an MS student basically takes courses the whole time and when they are finally competent enough to do research, they graduate and leave -- therefore, supporting them is not a good use of research grant money. I recently had an MS student funded by her job, and it was still a net loss for me, because I had to provide her with computer, lab space, and supplies; I spent a lot (A LOT) of time advising the student, as she wasn't very strong; I had to agree to this accelerated timeline that her job required; and in the end she produced what I would consider a very minimal thesis that I don't think is publication worthy. .

Something like an MA or equivalent (basically, an option where people can take specialized courses post BS, but without doing research for a thesis, and pay on their own way) is certainly fine, but as a means of doing research I think prevalent MS is not a good idea in most fields. (CS is an exception, I believe.)

Sounds like engineering is another exception, especially for work that doesn't have a long ramp up. In my case, I had a TA that paid for classes and essentially did two separate years, the first year was taking most of the required classes and the second year was almost exclusively research (and I only worked with my adviser for the second year). Obviously I had to leave the lab for the teaching part, but I did my grading at home to maximize time in the lab.

I also wonder if size of lab has a large impact. While my adviser had a significant orientation period, because there were 6 students going thru it (mostly PhD candidates), having an MS-only person didn't add any extra effort at that point. After that the adviser does have to spend time on the MS student, but again economies of scale helped (the lab rule was two students reviewed every paper/presentation before it was sent to the adviser).

My take on it is that while it's our job as mentors to help guide people towards their best success, it's paternalistic for the PIs to decide how many people get to try for a PhD degree. If the economics are favorable, i.e. there is $$ to support people and lots of people want to do it, they are grown adults who can choose their path in life as they see fit. We should be transparent about all the options, the upsides and downsides, but let them choose to do it if there are projects and money that can accommodate them.

There absolutely are abuses of this, and exploitative PIs who don't give a crap about what happens to their students. But they are not the majority, and rather than making people's choices for them by reducing the number of opportunities available, we should spend our time, energy and political capital to work on weeding out the A-hole exploiters and developing a better training culture overall.

I totally agree. In my field, most people go into a PhD planning on a non-academic career (and more move that direction after seeing what it is like!). Students graduating with PhDs from my department generally find good jobs in our field fairly quickly, so there is a demand for the training we are providing. I believe there are some fields that are overproducing PhDs, but even there, my preference is to provide opportunity for as many interested folks as we can pay for, and give applicants enough information to make a good decision for themselves.

We've been making slow but steady strides in making the grad student population more diverse in lots of ways, and my biggest concern in restricting opportunity is that we would go back to grad school populations that are mostly upper middle class. In my field, grad school is mostly opportunity cost, and even the people I know who left the field after a PhD don't regret their time in grad school. I'm sure there are some who do, but there are some who regret every sort of decision.

"Students graduating with PhDs from my department generally find good jobs in our field fairly quickly"

It sounds like your field is an exception. For many PhDs, this is not the case.

"my biggest concern in restricting opportunity is that we would go back to grad school populations that are mostly upper middle class."

Do you have any evidence for this? Because logically, it does not follow that restricting an incoming class to fewer students has to impact *how* those students are selected.

Why do so many parents want their kids to be doctors (MD)? If getting a PhD were like getting an MD, with ample opportunity for a well-paying job at the end, it seems to me that his would attract *more* students from lower-income backgrounds, not fewer. Today, a PhD in some sciences has become like the art and philosophy degrees that kids with limited means literally cannot afford to get.

I am in a physical science. My experience with placing students is echoed by my collaborators in other departments, for the most part (I do nothing remotely biomedical), as well as all available data on employment (which is admittedly not so good). The NSF's data on PhD outcomes is weak, but does not support the idea that there is a huge number of experimental science PhDs who can't find jobs. At least in 2014 (last data release).

At ProdigalU, we only accept students who have research experience, which already locks out students who can't get that experience for some reason (like that they have to work too many hours or there are no research opportunities at their school). In my field, research for credit during the academic year is common, so we mostly shut out students from smaller schools where there is no research, or students who transfer from community colleges and have no credit space. We are aware of this, but the risk of taking on a student who has no idea what research is like is too high given the funding realities right now.

In terms of slashing space reducing socioeconomic diversity, I am pretty confident of that--if we have to start making tighter selections on admission, we'll go by CGPA and CV. Wealthier students tend to have shinier CVs--they don't have to work, so can spend more time on schoolwork or volunteering if they desire. Students applying from "pedigree" schools are more likely to be wealthier as well. As shown by the current funding situation, humans tend to be more risk averse when resources are scarce. How can this not impact diversity in PhD programs?

I suspect MD programs also mostly pull from higher-income backgrounds, because med school admissions heavily favor students who test well, have high CGPA, and can volunteer. Besides, everything I have seen and experienced suggests that lower-income people tend to be much more reluctant to take on debt, which is an issue considering the $200,000+ debt load medical school can require.

I think many parents want their kids to be MDs because they think they know what doctors do from life experience and media, and because doctors are supposed to be paid very well. Some parents think they want their kids to be lawyers for mostly the same reasons, unless they have looked at the current employment situation for lawyers not in top ranked programs.

NIH funds support a hell of a lot more students and trainees than NSF, so if you want to make general statements about opportunities for PhDs, you simply can't ignore the biomedical field.

Also, it sounds like you and your colleagues already limit your entering class to mostly upper middle students anyways, so no big loss of opportunity for the lower-income ones at ProdigalU. Schools that truly prioritize diversity in STEM will continue to admit lower-income students, irrespective of whether they have 10 slots or 20 to fill.

Finally, I would not discourage a lower-income student from taking on debt to go to med school. I would certainly advise them against doing so to get a PhD, even in an "experimental" science, whatever the hell you think that means.

Thanks (and I liked your tragedy-of-the-commons comment on the previous post too). Agree that one has to find a comfort zone as a PI. Problem is there are a lot of a**holes out there whose comfort zones include over-grazing.

BTW, does anyone else find it amusing/ironic that NIH chose to name their Electronic Research Administration "commons"?

"it's paternalistic for the PIs to decide how many people get to try for a PhD degree"

Is it paternalistic for MDs or JDs to decide how many people get to try for those degrees? And if you don't have a problem with that, why is a PhD different?

"we should spend our time, energy and political capital to work on weeding out the A-hole exploiters...."

This is just wishful thinking, as the ones with the most power are precisely the A-hole exploiters, and academics are great at making excuses about why this is not the time/place to challenge someone, or this isn't the hill I want to die on, etc.

"Many PhDs, particularly in the sciences that we are talking about (*), pay pretty well for the level of experience."

Not if you consider that a person with a BS/BA could make 2x as much right out of school.

The number of MDs and JDs in programs aren't artificially limited either, they're driven by market factors like how many people want to do it and how many the system capacity can manage. Same as PhD programs generally are overall now. The paternalism would be to decide to limit it to some top-down number that was a lot lower than it would be if left to be driven by those supply and demand factors.

As for exploiters, it's only wishful thinking if people don't work on changing our culture. The whole point of this discussion is that I think it's more worthwhile to work on that than to work on deciding what single digit number to limit our PhD intakes to.

The number of MDs and JDs in programs aren't artificially limited either, they're driven by market factors

I don't think that this is quite correct for MDs. AFAIK you can't just decide to open a new medical school, at least in the US. In the state I used to live in, a rather prestigious institution has been trying for many years to start its own medical school and has been denied permission by the state.

It's different for JDs, which is why the employment outlook for new law grads is so grim.

Actually, MD programs are regulated, as Academic Lurker (next comment) suggests. At state universities, the State Boards of Education control how many students can be admitted to these programs, too. There are market forces governing those decisions, but its also a decision to actively limit the number trained in the US.

Uh OK. An experimental science is one where people do experiments. I was going for a subset of STEM, removing the social scientists, but perhaps should have been more explicit. The situation for engineers is really different from physical or life scientists, since they are so much better paid right off the bat with a BSE than someone with a BSc/BA in a related discipline, so the opportunity cost for grad school is much higher.

I was not suggesting to ignore NIH funded students--the NSF collects data for biomed PhDs as well. They run the Survey of Earned Doctorates and the Survey of Doctorate Recipients (links in my blog post here: theprodigalacademic.blogspot.com/2017/05/overproduction-of-phds-revisited-and.html). While the data has its flaws, there is nothing in there supporting an unemployment catastrophe for either physical scientists or biomedical scientists in what is available.

As for economic diversity right now, we actually have a fairly diverse student population at ProdigalU--not all community college students are credit capped when they transfer, and many students from all backgrounds get paid to do research at some point. I worry that we will lose this diversity if we cap spots, since students who work outside jobs do tend to have lower GPAs and less extra stuff on their CVs. There is no move to cap spots beyond the limits set by what we can support, but spots can be capped for us by a decrease in funding.

I don't think I ever said I thought going into debt for a PhD is a good idea--it isn't. I actually am not sure that going so far into debt for medical school is such a good idea either, unless you are SURE you want to be a doctor, and don't mind limiting your options based on compensation for a while. I do know at least one person who can't wait to get out from under their debt so they can quit medicine.

"While the data has its flaws, there is nothing in there supporting an unemployment catastrophe for either physical scientists or biomedical scientists in what is available."

Ok, you win. All those people on the internet claiming that they can't find jobs doing what they were trained to do are just a bunch of whiners -- losers, really. There is no problem. Perhaps you should ask your colleagues in the biomedical sciences -- those that are willing to be honest with you -- what jobs *their* students are getting right out of school. It might be an eye-opening experience for you.